Mammillaria (Pincushion or Nipple Cactus) is the genus name of an attractive type of succulent cactus plants native mostly to the southwest United States and Mexico with some having naturalized into the Caribbean.
There are around 300 species within the genus Mammillaria.
Many of the individual Mammillaria species look so much alike as to be almost indistinguishable. Others vary greatly in appearance and cultivation needs.
In this article, we discuss the care and uses of this interesting plant and share advice on selecting the right Mammillaria for your home, greenhouse, patio, yard, garden or windswept desert property.
What Are Mammillaria Related To?
These cacti are often confused with several other types of small cacti (e.g. Neolloydia, Epithelantha and Coryphantha). This confusion has led to as many as 400 different species being mistakenly identified in the past.
A great deal of meticulous research in the field, along with genetic analysis has gone into sorting out this jumble.
Now botanists are confident that the genus contains around 300 species.
You won’t find most of these species offered in nurseries, garden centers and shops.
The varieties for sale as houseplants are typically small and grow close to the ground in the wild. To recognize a true Mammillaria cactus, look for its spirally arranged, nipple-shaped tubercles.
Interestingly, the spines of true Mammillaria are arranged according to the Fibonacci sequence.
This means that each row of tubercles is equal in number to the sum of the two rows immediately above it.
When you view the plant from above, you should notice that it has a very organized and orderly appearance.
Growing Mammillaria Cactus Facts
Size & Growth vary greatly depending upon the species. Some Mammillaria top out at an inch high, others at a foot high.
Flowering & Fragrance vary greatly from one species to another. All grow in a crown-like formation surrounding the top of the plant.
Light & Temperature: Generally speaking, these plants like warm temperatures (50°-85° degrees Fahrenheit) and bright light.
Watering & Feeding should be sparse year round. During the spring, summer and early fall, water thoroughly when the soil is almost dry.
During the winter, reduce watering by half. Provide a half-strength feeding of a balanced cactus fertilizer at the beginning of spring and toward mid-summer.
Potting Soil & Transplanting: These cacti prefer a fairly rich, well-draining cactus mix. Repot or transplant infrequently as these plants do well when slightly root bound.
Grooming is Simple: Keep an eagle-eye out for any signs of rot, and cut it away immediately if you notice it. Otherwise, separate and repot pups when they become overcrowded.
USDA Hardiness Zone: Mammillaria are generally hardy in USDA zones 8-11; however, this may vary from species to species. Refer to the USDA Plant Profile Pages for more specific information.
The various species are native to habitats ranging from low desert to both cold and tropical forest settings. Their natural range extends across the southwestern US and throughout Central America.
How To Grow & Care For The Pincushion Cactus
Care instructions for this genus of cacti vary greatly depending upon the species you select and how you choose to use this succulent plant.
Rugged outdoor plants require very little care. Keeping a cactus Indoors is another matter entirely.
When you keep indoor cactus, be sure to set up a sunny location in a room with a south-facing window during the winter time.
This setting provides the most sunlight. A window location is typically a bit cooler than the rest of the room, and this cool temperature during the winter months is necessary to spur Mammillaria to bloom during the growing season.
In the spring and the summertime, vary the location to provide your cactus the most light and heat.
Giving your plant an outdoor vacation in direct sunlight is a good idea.
How Often Should Indoor Mammillaria Cactus Be Watered?
During the growing season, let the top couple of inches of soil dry out before watering. Water the plant thoroughly, allowing excess water to run off. If your plant has a drip tray, be sure to empty it. These plants should never stand in water.
How Long Can You Go Without Watering A Mammillaria Cactus?
In wintertime, cut back on watering. You should only water about once a month, and then quite sparingly. Just give the plant enough water to prevent having it shrivel up. Be sure to keep your plant at about 50 degrees Fahrenheit during the winter and provide plenty of light.
How Much Fertilizer Does A Mammillaria Need?
You can fertilize your Mammillaria with a specially formulated cactus fertilizer or a very weak solution of houseplant fertilizer that is low in nitrogen and high in potassium and phosphorus.
Don’t overfeed your cactus as this will encourage green growth and discourage blooming.
What Type Of Potting Soil Is Best For Mammillaria Cactus?
When you repot your Mammillaria, you can use a prepared cactus/succulent potting mix, or mix up your own combination of one part potting mix; one part coarse builder’s sand and one part loam.
When And How Often Do Mammillaria Bloom?
Only mature Mammillaria bloom, and when they do bloom they display an attractive crown of flowers surrounding the top of the plant.
Flowers come in a wide variety of colors, sizes and shapes, depending upon the species of Mammillaria.
Some of richly fragrant and very attractive to hummingbirds and other pollinators.
How Often Do Mammillaria Bloom?
In an ideal outdoor setting, these plants produce buds during one growing season and then go dormant through the winter and into the spring and early summer.
After the first summer rain, the buds open and the flowers last for about seven days. Healthy, happy Mammillaria may bloom several times during the growing season, always following a rain.
Flowers may mature into edible fruits. Some are tart and tasty, while others are quite bland. Generally speaking, these fruits are very small, and it is hard to gather enough to provide much nutrition.
How Long Does It Take Mammillaria To Mature?
It can take many years for a plant to mature, so you may not see a flowering plant for a very long time. You should also realize that desert cactus kept indoors may never bloom because they simply cannot get enough light. The only way of being sure you are getting a mature plant is to purchase one that is already in bloom.
When Should Mammillaria Cactus Be Repotted?
You should not need to repot your cactus more than once every couple of years. They do well when root bound but will need repotting if the cactus becomes top heavy or the pot becomes overcrowded with offsets.
Naturally, you should replace the soil every couple of years because it will become depleted and salts may build up from watering over time.
It is best to repot at the start of the growing season. Don’t water before repotting cactus as it is easier to knock away dry soil from the roots, and potting in dry soil helps prevent root rot.
Examine the roots carefully and cut away any portions that appear to be dead or rotten. Treat the areas you cut with a spritz of hydrogen peroxide or a fungicide.
Put the plant into its new pot and surround it with your prepared cactus mix. Spread the roots out to give them room to grow. Don’t water right away. Wait about a week and then give the plant a light watering. Doing this helps prevent root rot.
How Do You Propagate Mammillaria?
These cacti are easy to propagate either from seed or using offsets (pups). The pups spring up in clusters around the base of the parent plant. To propagate them, remove them carefully using a very sharp, sterile blade, or simply pull them away.
Lay the offsets on a clean paper towel in a sheltered, airy setting for a few days. This will allow a callus to form over the cut or area where the pup was separated from the parent plant.
When a callus has formed, you can put the pup into its own pot. Keep it in a warm, sheltered place with bright, indirect sunlight until it takes root. This may take a few days or a few weeks. Once the plant has established roots, you can treat it as a mature plant.
What Are Some Common Pests & Problems Affecting Mammillaria?
Most problems with cactus grown as houseplants involve fungal or bacterial diseases that are caused by excessive watering.
This is why it is very important to establish a sparing watering schedule and observe your plants carefully for any signs of rot.
These include black spots around the base of the plant and mushy flesh.
In addition to problems caused by overwatering, common houseplant pests are sometimes problematic. Among these are:
- Root Mealy Bugs
- Fungus Gnats (small black flies)
- Spider Mites
- Mealy Bugs
- Scale Insects
It can be very hard to get these pests under control once they are established because they are very small and hide quite effectively. Some of these pests have protective coatings that make it difficult to reach the actual insect with a pesticide or natural treatment.
To make matters worse, many common plant pests have developed resistance to commercial pesticides.
That’s why it is smart to maintain an Integrated Pest Management (IPM) strategy when dealing with any and all garden and houseplant pests.
Follow These 9 Smart IPM Tips!
#1 – Keep your plants healthy by providing the right environment and the correct care. Healthy plants are better able to resist disease and pests.
#2 – Always quarantine new plants for at least three weeks to avoid bringing in illness or hitchhikers. If you discover problems with a new plant, keep it separate and treat it or toss it.
#3 – Use natural treatments first. Spider mites and mealybugs can often just be washed off with a strong spray of water. Remember to cover the soil with plastic to prevent overwatering your cactus in the process.
#4 – Examine and clean the roots of cactus when repotting or transplanting. Root mealybugs can be washed off the roots with a strong spray of water. Blot excess water from the roots and allow them to air dry for a few hours before continuing with repotting or transplanting.
#5 – Examine your cacti often for signs of scale and mealybugs. If you see just a few, you may be able to remove them easily with a cotton swab dipped in rubbing alcohol.
#6 – You can spray your cacti occasionally with a diluted rubbing alcohol solution. Mix up one part alcohol with three parts water for a spray that will help deflect these pests. Be sure to test spray a small spot on the plant before spraying the entire plant. Some cacti are sensitive to rubbing alcohol.
#7 – Trap fungus gnats with yellow sticky traps or set up small jars of apple cider vinegar (ACV) to trap them. To do this, you’ll need a small jar with a lid. Punch small holes in the lid (or use an old spice bottle that already has a lid with holes).
Pour about half an inch of ACV into the jar and screw on the lid. Place the jar among your plants. Gnats will fly in to get the ACV and won’t be able to get out, so they’ll drown in the ACV.
#8 – Make milder insecticides your first choice, applied sparingly and only when necessary. Neem oil and pyrethrins are good choices.
#9 – If you have a problem with pests that are hard to reach with sprays, use systemic insecticides such as acephate and imidacloprid. Follow packaging instructions carefully.
How Do You Tell If You’re Overwatering Mammillaria Cactus?
Remember that cactus doesn’t just tolerate drought, they need it. Their roots are very susceptible to rot, and it’s easy to kill them with too much water.
It may not seem that way at first, though. When a cactus first receives too much water, it may become very plump and begin putting out new growth.
Even when this is happening above ground, the roots are sure to be suffering under the soil.
When cactus roots become waterlogged, they start dying and rotting. Gradually, the rotten roots cause the seemingly healthy plant to start deteriorating.
The flesh becomes discolored and begins to soften. When this starts to happen, it may be too late to save the plant.
That’s why it is so important to monitor your cactus carefully and look for soft, discolored spots around the base of the plant.
How Do You Save An Overwatered Mammillaria Cactus?
If your cactus is showing signs of rot around the roots, you must remove it from its pot and use a sharp, sterilized blade to cut away the rotten parts.
Work from the bottom up, removing thin slices until you reach fresh, unaffected flesh.
Seal off the open cut with cornstarch, and allow the cutting to dry on a paper towel for a period of several weeks.
If your cutting is going to survive, it will produce a few roots during this time.
When this happens, carefully brush away the cornstarch and provide the cutting with its own new pot and fresh cactus mix.
Best Uses For Mammillaria Cactus Indoors or Outdoors
There are so many different types of Mammillaria cactus that, no matter what your setting or purpose, you can surely find a variety to suit your needs.
Some species are quite delicate and suited to a sheltered indoor setting. Some are rugged, low growing and fast-spreading and make marvelous additions to rock gardens and other challenging settings.
Still, others grow quite tall and exhibit isolated growth patterns, making them ideal as specimen plants in a cactus garden or centrally located planter.
A mini cactus garden is a good way to display several different varieties of Mammillaria indoors!
This video shows many of the more rugged varieties in their natural habitat and could inspire some great ideas for using Mammillaria in your own desert landscape.
What Are The Most Popular Mammillaria Varieties?
There are multitudinous species of Mammillaria (Pincushion) cactus. All flower freely, and those that are readily available commercially are quite easy to take care of.
Many species of Mammillaria have very colorful, descriptive names based upon their appearance.
Still, others do not have common names in English but do have common names in Ukrainian, Russian, Spanish and/or Swedish.
Very often the common names are used interchangeably to refer to similar species within the genus.
Some have no common names at all. Here are just a few representatives of this interesting and abundant genus of cacti.
14 Most Popular Mammillaria Varieties
#1 – Mammillaria tetrancistra (common Fishhook cactus) is found in the Sonoran and Mojave deserts in the northern part of Mexico and in the southwestern US. It grows happily in a wide variety of desert settings. This plant has soft, white spines with a central, curved spine. Flowers are showy and pink.
#2 – Mammillaria backebergiana (Pincushion Cactus, known in Ukraine as Bakerberg Mammillaria) is a columnar cactus. Its spines are yellow or yellowish/brown. The cactus produces large, purple flowers.
#3 – Mammillaria plumosa (feather cactus) is a low-growing, clumping plant. It forms dense mounds that can cover quite a bit of ground with close-set, white, feathery spines. The flowers are off-white/yellow and sweetly fragrant.
#4 – Mammillaria spinosissima (Red-Headed Irishman) is very common the world over. It is easy to find this cactus offered in nurseries and other purveyors of plants. The plant has reddish, rusty colored spines.
#5 – Mammillaria baumii (Pincushion Cactus)is a low-growing, clumping species with dense spines which obscure the stems. The funnel-shaped flowers are golden yellow and very fragrant.
#6 – Mammillaria elongata (Gold Lace Cactus, Ladyfinger Cactus) is available in a variety of shapes and colors. One version has copper-colored spines, another has regular white/tan spines, still others are oddly shaped (crested and brain-shaped). Flowers may be either pink or yellow.
#7 – Mammillaria zeilmanniana (Rose Pincushion Cactus)grows in clusters covered with dense, white “hair”. The flowers are deep red/violet.
#8 – Mammillaria bocasana (Snowball or Powder-puff Cactus)is extremely hardy. This cactus grows in clumps and is covered with dense, soft-looking white “hair”. Be careful, though, sharp fish-hook spines are hidden beneath the hair. The flowers of this species are quite small and may be white, yellow or pink.
#9 – Mammillaria candida (Snowball Pincushion) is a clumping cactus covered with pink-tipped, white spines. Cream-colored flowers emerge early in spring and transition to pink as the season progresses.
#10 – Mammillaria elegans (Pincushion Cactus)is a globular cactus hailing from Mexico. The cactus has white spines, soft wool and deep magenta flowers that last for an extended period of time.
#11 – Mammillaria hahniana (Old Lady Cactus or Superba) grows as a solitary specimen. This cactus is spherical in shape and produces dense, short white hairs. Flowers are reddish/purple. These very attractive cacti are hardy, carefree and easy to grow.
#12 – Mammillaria matudae (Crawling Log or Giant Snake) has a mounding growth habit that manifests as long, snaking stems. https://hgic.clemson.edu/factsheet/indoor-cacti/
#13 – Mammillaria longimamma (Nipple Cactus, Finger Mound, Peyotillo)is unusual looking and quite popular with its “long nipples” (longimamma). The spines of this cactus are thin and sparse. Its flowers are a lovely, bright yellow.
#14 – Mammillaria rhodantha (Rainbow Pincushion)is a very popular, easy-to-find, easy-to-grow cactus. It has a solitary growth habit and may have either red or golden spines. Its flowers are pink.
13 Less Readily Available Mammillaria Varieties
#1 – Mammillaria grahamii (Fishhook Pincushion or Graham’s Nipple cactus) is also called the Cabeza de Viejo (Old Man’s Head) in Spanish. This cactus grows in abundance in the Arizona Upland, where it can be found amidst debris underneath various desert shrubs.
This cactus prefers partial shade. It is a rugged, robust cactus that grows abundantly in challenging settings throughout the deserts of the southwestern US and Mexico. It can do well in landscape settings such as desert gardens and rock gardens.
#2 – Mammillaria compressa (Mother of Hundreds)grows in rather large mounds. Its spines are sparse, and its flesh is a dull, pale shade of green. Flowers are pink.
#3 – Mammillaria decipiens (Bird’s-nest Pincushion) has an interesting, low-growing growth habits. It’s limbs are prominently nippled, and its long, curling spines whorl together to create a bird’s nest appearance.
#4 – Mammillaria formosa (Owl Eyes or Royal Cross) is a globular plant with extremely short spines that do not stick in skin.
#5 – Mammillaria karwinskiana (Owl Eyes or Royal Cross)is a solitary specimen plant that produces offsets in a slow and sporadic manner. Its spines are sparse, and its flowers may be either bright yellow or pink.
#6 – Mammillaria geminispina (Twin Spined Cactus) comes in several forms. Some have long spines, and others have short spines. Some have a clumping growth habit, and others are columnar and grow in small groups. Some types have pink flowers, and others have light yellow flowers.
#7 – Mammillaria matudae (Thumb Cactus)has a tall, columnar growth habit. The plant tends to get top-heavy and may fall over if it is not braced. Spines are extremely short and close-spaced. The flowers are bright pink, and this species can be counted on to bloom year-round.
#8 – Mammillaria gigantea (Ukrainian common names Mammillaria Huge, Giant or the Giant) is a very large (4′ high) globular species with strong, fierce spines and stunningly beautiful flowers that range in color from deep pink to a silvery shade of yellow. This rugged plant may grow as a solitary specimen or grouped with others. It thrives in hot, dry sunny desert settings.
#9 – Mammillaria mystax (Cactus Mystax) is a barrel-shaped cactus with a solitary growth habit. It is very similar to Mammillaria gigantea. These hardy plants have short, thick spines and a very orderly, architectural appearance. This is a rugged species that does well with hot sun and very little water.
#10 – Mammillaria vetula/Mammillaria gracilis (Thimble Cactus) is a very small and fragile species. It is globe-shaped and tends to produce lots of little offsets that fall off very easily if the plant is moved. The spines of this plant are pale colored and flat, so handling the plant does not cause injury. Even so, this plant is not usually kept in private collections because of its tendency to fall apart when moved. It’s best left in its natural habitat.
#11 – Mammillaria nivosa (Woolly Nipple Cactus) is a mat-forming cactus that can produce deceptively soft looking, wooly white mats a little over a foot wide. Its flowers are yellow and open at night. Flowers become interesting, deep red, club-shaped fruits.
#12 – Mammillaria mainiae (Counter-Clockwise Fishhook) is native to the washes, badlands and valleys of the Sonoran desert. This globe-shaped, small, slow-growing cactus thrives in rocky soil on slopes, hillsides and sand dunes. It likes lots and lots of sun and very little water. It is not a good candidate for container planting, but if you try, you must use a mineral based potting medium, and keep the plant completely dry during its winter dormancy.
#13 – Mammillaria dioica (Strawberry Cactus, Strawberry Pincushion, California Fishhook) grows naturally in Baja and northwestern Mexico.
The plant prefers rocky soil and often springs up in crevices between larger stones. This very small cactus may grow individually or in a grouping of small stems.
Maximum height for this species is 6″, but this is rare. It has short, firm “nipples” with an aureole of straight white spines. The central spine is longer and hook-shaped. The plant produces very small, yellow flowers.
Species without common names include:
Mammillaria theresae is a very small, very hardy species that produces almost non-existent spines. Showy flowers are a lush shade of violet/pink.
Mammillaria voburnensis grows to be about three inches high. It is a globe-shaped plant with interesting deep green/maroon flesh. The plant produces lots of offsets. Flowers are small and nondescript.
Mammillaria supertexta and Mammillaria albilanata look very much alike. They have very short, close-set spines that do not cause injury when the plant is handled. These species grow in a columnar shape. They produce offsets slowly. Both have pretty pink flowers.
For images of even more Mammillaria species, along with some good inspiration for container planting, view this Mexican video en Espanol!
Mammillaria Buying Tips
When shopping for Mammillaria or any cactus, there are a few things you can do to be sure of making the best purchase.
Buy your Mammillaria from a reputable dealer. Don’t gather them in the wild or purchase them from someone who may have done so. Cactus poaching is often illegal and leads to species extinction, which is a big problem.
Be sure the soil is dry. Remember that an overwatered cactus may look good on the top (for now) but bad things are happening underground.
Be sure that cactus is standing up straight. Leaning can be a symptom of lack of light or of root rot.
Bring a box to carry your cactus home. A plastic tote or cardboard box will protect your cactus (and you) from damage on the trip home.
It will keep the plant upright and prevent spilling soil out in your vehicle.
If there happens to be a little snake hiding in the soil (as has happened to this writer) it won’t be able to slither under the seat of your car if you put your new cactus in a box or tote.
Mammillaria Cactus Are Fascinating And Easy To Grow
Even though there are so many species, and a few of them are a bit picky, if you have had good luck with succulents and cactus in the past, you should be able to grow Mammillaria with great ease.
Just remember to place your plants correctly in winter and reduce watering to give them a good rest period.
Provide lots of bright sunshine and warm temperatures in the spring and summer, and before you know it your cacti will reward you with beautiful, fragrant blossoms.
Remember that a light touch on the fertilizer and the watering can are your most important keys to success with Mammillaria.